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Dietary supplement

Vitamin K2 Ingredients & Drug Interactions

by Douglas Laboratories

Vitamin K2 label
See full label image
Capsule Category: Vitamin
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Vitamin K2 against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

Vitamin K2 is a dietary supplement by Douglas Laboratories with 1 active ingredient. Its ingredients are commonly taken for supporting normal blood clotting, bone health, heart and vascular health.Based on those ingredients, 2 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Vitamin K2. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Vitamin K2 by Douglas Laboratories

Ask about any prescription or over-the-counter medication and we check it for interactions with Vitamin K2 by Douglas Laboratories — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Vitamin K2 by Douglas Laboratories

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: vitamin K2, a form of vitamin K that your body uses to activate proteins involved in blood clotting and bone health. The capsule also contains several inactive ingredients — microcrystalline cellulose, hydroxypropyl methylcellulose, calcium citrate, vegetable stearate, and silica — which are fillers and binders that hold the supplement together.

Does it work?

Strong evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed

This product doesn't appear to be marketed for a specific use, so we graded Vitamin K's overall clinical evidence instead.

Strong

Strong clinical evidence supports Vitamin K for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Hemorrhagic disease — rated "Effective" (Natural Medicines).
  • On file: Hypoprothrombinemia — rated "Effective" (Natural Medicines).
  • On file: Warfarin anticoagulation — rated "Effective" (Natural Medicines).
  • On file: Vitamin K-dependent clotting factors deficiency (VKCFD) — rated "Effective" (Natural Medicines).
  • On file: Osteoporosis — rated "Possibly Effective" (Natural Medicines).

Vitamin K2 is effective for treating vitamin K-dependent clotting factor deficiency, hypoprothrombinemia (a blood clotting disorder), hemorrhagic disease, and managing warfarin anticoagulation. For osteoporosis, the evidence shows it may be helpful, though more research is needed to be certain.

The evidence, ingredient by ingredient Vitamin K

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

When taken by mouth, vitamin K is generally well tolerated. The most common side effects are mild gastrointestinal symptoms — nausea, diarrhea, stomach upset, and abdominal pain — and only a small number of people experience them.

The safety data notes that normal dietary amounts are fine, but you should check with your doctor before taking supplements, especially if you have any health conditions or take medications.

Side effects, ingredient by ingredient Vitamin K

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Vitamin K.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 2 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Warfarin (Coumadin) and other blood thinners (anticoagulants) are the main concern — vitamin K can reduce how well they work. Check with your pharmacist or doctor before adding this product if you take any blood thinner.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with strong clinical evidence behind its ingredients' uses. Major medication interactions have been identified, and safety information is well characterized.

Vitamin K2 is a straightforward supplement for people with clotting disorders or those whose doctors have recommended it. If you take warfarin or any other blood thinner, you must talk with your pharmacist or doctor before starting — this is non-negotiable.

Otherwise, if you're generally healthy and not on blood thinners, run your medications through our checker first.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Aug 23, 2020.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Vitamin K2, straight from the product label.

Brand Douglas Laboratories
Barcode (UPC) 310539036761
Net contents 60 Vegetarian Capsules
Market status On market
Date entered into DSLD Aug 23, 2020
DSLD ID 232250
Product type Vitamin
Supplement form Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Vitamin K2 by Douglas Laboratories, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Vegetarian Capsule(s)
Maximum serving Sizes:
1 Vegetarian Capsule(s)
Servings per container
60
UPC/BARCODE
310539036761
IngredientAmount% DV
Vitamin K290 mcg--

Other ingredients: Microcrystalline Cellulose, Hydroxypropyl Methylcellulose, Calcium Citrate, Vegetable Stearate, Silica

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Suggested Usage: As a dietary supplement, adults take 1 capsule daily or as directed by your health professional.

Precautions

Warning: If you are pregnant, nursing, have any health condition or taking any medication, consult your health professional before using this product. Consult a health professional prior to use if you are taking blood thinners.

Keep out of the reach of children.

Use only if safety seal is intact.

Storage

Store in a cool, dry place.

Formulation

Gluten-free, Non-GMO

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

General Statements

Contents may not fill package in order to accommodate required labeling. Please rely on stated quantity. Scan to learn about our manufacturing excellence

Formula

Menaquinone-7

FDA Statement of Identity

Dietary Supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Vitamin K2 by Douglas Laboratories label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Vitamin K2 label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Vitamin K2 by Douglas Laboratories

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Vegetarian Capsule(s) Dosage formCapsule Servings per container60 Amounts shown are per serving.

Vitamin K2

Interacts with
2 drugs
90 mcg per serving Form: Menaquinone-7

Vitamin K is an essential nutrient your body needs for normal blood clotting and to support healthy bones. Most people get enough from food, but suppl...

Vitamin K2 monograph & interactions

Other (inactive) ingredients: Microcrystalline Cellulose, Hydroxypropyl Methylcellulose, Calcium Citrate, Vegetable Stearate, Silica. These complete the product’s ingredient list but are not active constituents.

Interaction report

Vitamin K2 by Douglas Laboratories Drug Interactions

Want to check YOUR meds against Vitamin K2?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
2Drugs
2 Major

Ingredients driving the most interactions

Vitamin K2 2

Individual Drug Interactions

The ingredients in Vitamin K2 interact with 2 drugs. Click any drug to see the details.

1 of the 1 ingredient in Vitamin K2 interact with drugs. Each result below shows which ingredient is responsible. Vitamin K2

Each ingredient & the kinds of drugs it affects

For each ingredient in Vitamin K2 with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Vitamin K21 drug type · 2 drugs

Warfarin (Coumadin)

Vitamin K can antagonize and reverse the therapeutic effects of warfarin.
Vitamin K antagonizes the effects of warfarin. Excessive vitamin K intake, either from supplements or from changes in the diet, can reduce the anticoagulant effect of warfarin.

Likelihood Likely Evidence C
Vitamin K2 full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Vitamin K2, from the product label.

Douglas Laboratories

See all Douglas Laboratories products
Name
Douglas Laboratories
Street Address
600 Boyce Road
City
Pittsburgh
State
PA
ZipCode
15205
Phone Number
1.800.245.4440
Web Address
www.douglaslabs.com
Pharmacist Counseling Corner

Vitamin K2 by Douglas Laboratories: Common Questions

Does Vitamin K2 by Douglas Laboratories interact with any medications?
Yes. Based on its ingredients, Vitamin K2 has a known interaction with 2 medications, including 2 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Vitamin K2 contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Can I take this if I'm on warfarin?
No — not without talking to your doctor first. Vitamin K directly interferes with warfarin and can make it less effective at preventing clots. Your doctor may want to monitor you closely or adjust your dose if you need both. Don't start this on your own.
What's the difference between vitamin K1 and K2?
The facts we have don't break down differences between the forms. What we know is that vitamin K in general — the form in this product is K2 — works for blood clotting disorders and may help with bone health. If you want to understand which form is right for you, ask your pharmacist.
Will this cause side effects?
Most people don't have problems with it when taken by mouth. Some people do experience mild nausea, diarrhea, stomach upset, or abdominal pain, but these are not common. If you notice any of these, let us know.
Is it safe to take during pregnancy or while breastfeeding?
The safety data shows vitamin K is likely safe in pregnancy and lactation. That said, any supplement decision during pregnancy or breastfeeding is individual — talk with your doctor or midwife before starting, even if the data looks reassuring.
Can I take this for bone health?
The evidence suggests vitamin K may help with osteoporosis, but the data isn't as strong as it is for clotting disorders. If bone health is your goal, talk with your doctor about whether this makes sense for you and what dose to use.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Not sure if Vitamin K2 is safe with your meds?

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Vitamin K2 label
Go deeper

The Full Monographs Behind Vitamin K2’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Vitamin K

Interacts with 2 drugs

Vitamin K is an essential nutrient your body needs for normal blood clotting and to support healthy bones. Most people get enough from food, but supplements are sometimes used for deficiency...

Read the full Vitamin K monograph →
Sources

Sources & How We Checked

Vitamin K2's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 11 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Vitamin K 11 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  3. Crowther MA, Ageno W, Garcia D, et al. Oral vitamin K versus placebo to correct excessive anticoagulation in patients receiving warfarin: a randomized trial. Ann Intern Med. 2009;150(5):293-300. PubMed
  4. Dietary vitamin K guidance: an effective strategy for stable control of oral anticoagulation? Nutr Rev. 2010;68(3):178-81. PubMed
  5. Kim JS, Nafziger AN, Gaedigk A, et al. Effects of oral vitamin K on S- and R-warfarin pharmacokinetics and pharmacodynamics: enhanced safety of warfarin as a CYP2C9 probe. J Clin Pharmacol. 2001 Jul;41(7):715-22. PubMed
  6. Riegert-Johnson, D. L. and Volcheck, G. W. The incidence of anaphylaxis following intravenous phytonadione (vitamin K1): a 5-year retrospective review. Ann.Allergy Asthma Immunol. 2002;89(4):400-406. PubMed
  7. Dezee, K. J., Shimeall, W. T., Douglas, K. M., Shumway, N. M., and O'malley, P. G. Treatment of excessive anticoagulation with phytonadione (vitamin K): a meta-analysis. Arch.Intern.Med. 2-27-2006;166(4):391-397. DOI
  8. Dentali, F., Ageno, W., and Crowther, M. Treatment of coumarin-associated coagulopathy: a systematic review and proposed treatment algorithms. J.Thromb.Haemost. 2006;4(9):1853-1863. PubMed
  9. Caluwé R, Vandecasteele S, Van Vlem B, Vermeer C, De Vriese AS. Vitamin K2 supplementation in haemodialysis patients: a randomized dose-finding study. Nephrol Dial Transplant. 2014;29(7):1385-90.
  10. Huang ZB, Wan SL, Lu YJ, Ning L, Liu C, Fan SW. Does vitamin K2 play a role in the prevention and treatment of osteoporosis for postmenopausal women: a meta-analysis of randomized controlled trials. Osteoporos Int. 2015;26(3):1175-86. PubMed
  11. Hunnali CR, Devi U, Kitchanan S, Sethuraman G. Three Different Regimens for Vitamin K Birth Prophylaxis in Infants Born Preterm: A Randomized Clinical Trial. J Pediatr 2023;255:98-104. PubMed

See these in context on the Vitamin K monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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